AMESIUM RUTA-MURARIA. 255 



rior as Horace does in " immoritur studiis " — " he is always at 

 his books ; " or he may have -written immoratur,- — " it lives" on 

 brick walls, thus pointing out its favourite locality. So care- 

 fully observant a man as DUlenius must have frequently seen 

 it flourishing in the crumbling mortar filling the interstices of 

 brick buildings : we need wander no further from London than 

 to the wall of Greenwich Park, to see it flourishing abundantly 

 upon bricks ; and nothing can be more common than to see it 

 on the brick walls of fruit-gardens, particularly selecting the 

 uppermost line of inortar, which may perhaps be protected by 

 a coping of brick : this is ever a favourite station for cobwebs 

 and wall rue. 



The radicles of Asplenium Euta-muraria are wiry and black : 

 the caudex is black, tufted, and clothed with bristly scales : the 

 fronds make their appearance in May and June, arrive at matu- 

 rity in September, and continue perfectly green throughout the 

 winter, and until the ensuing May : they are always fertile. 

 The stipes is black or dark purple, very smooth and shining, 

 and generally longer than the frond. The normal form of the 

 frond is triangular and pinnate ; the pinnse being alternate and 

 also pinnate : the pinnules are of varied form, but mostly some- 

 what diamond-shaped ; they are stalked, and resemble so many 

 little leaves ; their exterior margin is generally serrated or cre- 

 nate. The veins radiate from the stalk to the exterior margin 

 of the pinnule, and to them are attached the elongate lines of 

 capsules, two, three, four, or even five on a pinnule : these are 

 at first covered by an elongate, linear, white involucre, the free 

 margin of which generally faces the median line of the pinnule, 

 and is jagged and uneven; this is soon pushed aside by the 

 swelUng capsules, turned back, and finally lost, the back of the 

 pinnule becoming eventually nearly covered by a dense, dark 

 brown mass of seed. 



